<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        .done{
            text-decoration: line-through;
            color: grey;
        }
        .todo li{
            width: 200px;
            height: 20px;
            padding: 3px;
            position: relative;
        }
        .todo li button{
            position: absolute;
            top: 0;
            right: 0;
        }
        button:hover{
            cursor: pointer;
        }
    </style>
</head>
<body>
        <h4>待办事项</h4>
        <input type="text" name="input" placeholder="请输入待办事项">
        <button>保存</button>
        <h4>待办</h4>
        <ol class="todo">
            <li>
                <span>eat</span>
                <button>完成</button>
            </li>
            <li>
                <span>sleep</span>
                <button>完成</button>
            </li>
            <li>
                <span>code</span>
                <button>完成</button>
            </li>
            
        </ol>
        <h4>已完成</h4>
        <ol class="done">
            <li>one</li>
            <li>two</li>
            <li>three</li>
        </ol>
</body>
</html>